The research aims to analyze the runoff in the urban area of Santa Maria (RS), using the curve number model, developed by the Soil Conservation Service (SCS) with help of geoprocessing techniques. This methodology is based on integrated analysis of information regarding to land use and land cover, reclassified types of soil according to hydrologic groups proposed by SCS. The HRC/CBERS images were segmented and classified in order to obtain the land use and cover map of the urban area of Santa Maria, and the Aster digital elevation model was used in order to get information about the study area declivity. The map of hydrologic soil groups was developed from a map of existent soil types, these ones were reclassified according to their textural characteristics. For every combination of hydrological groups and land use and land cover classes were aggregated values corresponding to its potential runoff (curve number). Finally, it was done the integration of this potential runoff map with the declivity information, in order to identify the most potential areas to flooding in the urban area of Santa Maria. The application of curve number model was efficient to get the characteristics of the runoff and to identify the potential urban flooding areas in the study area. The satellite images and the GIS were very efficient tools in the development of the land use and land cover, runoff and declivity maps.